/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.sql.impl;



import org.apache.calcite.schema.Function;

import org.apache.calcite.schema.TranslatableTable;

import org.apache.calcite.schema.impl.TableMacroImpl;



import java.lang.reflect.Method;



/** Unified-customized facade behind {@link Function} to address BEAM-5921. */

class UdfImpl {



  private UdfImpl() {}



  /**

   * Creates {@link org.apache.calcite.schema.Function} from given class.

   *

   * <p>If a method of the given name is not found or it does not suit, returns {@code null}.

   *

   * @param clazz class that is used to implement the function

   * @param methodName Method name (typically "eval")

   * @return created {@link Function} or null

   */

  public static Function create(Class<?> clazz, String methodName) {

    final Method method = findMethod(clazz, methodName);

    if (method == null) {

      return null;

    }

    return create(method);

  }



  /**

   * Creates {@link org.apache.calcite.schema.Function} from given method.

   *

   * @param method method that is used to implement the function

   * @return created {@link Function} or null

   */

  public static Function create(Method method) {

    if (TranslatableTable.class.isAssignableFrom(method.getReturnType())) {

      return TableMacroImpl.create(method);

    } else {

      return ScalarFunctionImpl.create(method);

    }

  }



  /*

   * Finds a method in a given class by name.

   * @param clazz class to search method in

   * @param name name of the method to find

   * @return the first method with matching name or null when no method found

   */

  static Method findMethod(Class<?> clazz, String name) {

    for (Method method : clazz.getMethods()) {

      if (method.getName().equals(name) && !method.isBridge()) {

        return method;

      }

    }

    return null;

  }

}